The present invention relates to a microdevice and to a method of manufacturing the microdevice. The invention is further directed to a method and device for withdrawing or delivering a substance transdermally to a patient. The invention is also directed to a method and apparatus for enhancing the penetration of a microneedle array.
Various devices have been proposed for sampling and delivering of substances such as pharmaceutical agents and drugs transdermally. Although the subcutaneous sampling and delivery methods using a cannula are effective for many applications, the pain normally induced by the cannula has prompted the development of less painful delivery methods.
The skin is made up of several layers with the upper composite layer being the epithelial layer. The outermost layer of the skin is the stratum corneum that has well known barrier properties to prevent molecules and various substances from entering the body and analytes from exiting the body. The stratum corneum is a complex structure of compacted keratinized cell remnants having a thickness of about 10-30 microns. The stratum corneum forms a waterproof membrane to protect the body from invasion by various substances and the outward migration of various compounds.
The natural impermeability of the stratum corneum prevents the administration of most pharmaceutical agents and other substances through the skin. Numerous methods and devices have been proposed to enhance the permeability of the skin and to increase the diffusion of various drugs through the skin to can be utilized by the body. Typically, the delivery of drugs through the skin is enhanced by either increasing the permeability of the skin or increasing the force or energy used to direct the drug through the skin.
Another method of sampling and delivering various substances through the skin is by forming micropores or cuts through the stratum corneum. By piercing the stratum corneum and delivering a drug to the skin in or below the stratum corneum, many drugs can be effectively administered. In a similar manner, some substances can be extracted from the body through cuts or pores formed in the stratum corneum. The devices for piercing the stratum corneum generally include a plurality of micron size needles or blades having a length to pierce the stratum corneum without passing completely through the epidermis. Examples of these devices are disclosed in U.S. Pat. No. 5,879,326 to Godshall et al.; U.S. Pat. No. 5,250,023 to Lee et al., and WO 97/48440.
The above-noted devices that include micron-sized needles or blades can be effective in delivering or sampling of substances in the body. However, these needles and blades having a length a few microns to a few hundred microns typically do not penetrate skin to a uniform depth. The natural elasticity and resilience of the skin will often result in the skin being deformed by the needles rather than pierced. A microneedle array when pressed against the skin often results in the outermost needles penetrating the skin while the innermost needles do not penetrate or only penetrate to depth less than the outermost needles.
The prior methods and devices for the transdermal sampling and administration of substances have exhibited limited success. Accordingly, a continuing need exists in the industry for an improved device for the sampling and administration of various drugs and other substances to the body.
The present invention is directed to a method and apparatus for the transdermal sampling or delivery of a substance though the skin of a patient. The invention is further directed to a method of manufacturing and assembling a device for delivering or withdrawing a substance through the skin of a patient. In particular, the invention is directed to a method and apparatus for delivering a pharmaceutical agent such as a drug or vaccine, to the stratum corneum of the skin to a sufficient depth where the pharmaceutical agent can be absorbed and utilized by the body.
Accordingly, a primary object of the invention is to provide a device having a skin penetrating member and to a method of penetrating the skin for sampling or delivering a substance through the skin substantially without pain to the patient.
Another object of the invention is to provide a device having a plurality of microtubes, needles, microneedles, blades or lancets for piercing the stratum corneum of the skin for withdrawing or delivering a substance though the skin of a patient.
A further object of the invention is to provide a device having at least one skin penetrating member and a device for enhancing the penetration of the skin.
Another object of the invention is to provide a device for sampling or delivering a substance to a patient where the device has a support and a microneedle device bonded to the support.
A further object of the invention is to provide a device for withdrawing or delivering a substance where the device includes a skin penetrating device and a vacuum port for applying a vacuum to enhance penetration of the skin by the skin penetrating device.
A still further object of the invention is to provide a method for enhancing skin penetration by a skin penetrating device in a target area by applying a vacuum to the surface of the target area and the skin penetrating device.
Another object of the invention is to provide a method of assembling a device comprising fitting a microdevice into a recessed area in a support and applying a bonding agent to the recess to wick between the microdevice and the support.
Still another object of the invention is to provide a method of bonding a microdevice to a support, where the support includes a recessed area and a channel having one end communicating with the channel, the method comprising fitting the microdevice in the recessed area and applying a bonding agent to the channel to flow into a gap between the support and the microdevice.
These and other objects of the invention are substantially attained by providing a method for forming a device for delivering or withdrawing a substance through the skin of a patient. The method comprises the steps of: providing a support having a bottom face with a recessed area having a dimension less than a dimension of said bottom face, positioning a skin penetrating device in said recessed area of said support. The skin penetrating device has a base and at least one skin penetrating member, the base has a dimension less than said dimension of said recessed area. A bonding agent is applied to at least one location between said support and said base in said recessed area, where the bonding agent has a viscosity to wick between the base and the support.
The objects and advantages of the invention are further attained by providing a method of withdrawing a substance or delivering a substance through the skin of a patient, said method comprising providing a support having a central passage, a bottom face, and a skin penetrating device on said bottom face, said central passage being in communication with said skin penetrating device, positioning said support on the skin of a patient with said bottom face of said support and said skin penetrating device contacting said skin, reducing the pressure in an area between said support and said skin to draw said skin toward said skin penetrating device and to cause said skin penetrating device to penetrate said skin, and withdrawing or delivering a substance through the skin of said patient.
Another object of the invention is to provide a device for delivering or withdrawing a substance from a patient, said device comprising: a support member having a bottom face and a recessed area having a dimension less than a dimension of said bottom face, a skin penetrating device having a base and at least one skin penetrating member, said base being positioned within said recessed area of said support, and a bonding material attaching said skin penetrating device to said support member and filling a space between said recessed area and said base of said skin penetrating device.
The objects, advantages and other salient features of the invention will become apparent from the following detailed description which, taken in conjunction with the annexed drawings, discloses preferred embodiments of the invention.